In the past thermal bonding conjugate fibers that can be formed by thermal fusion bonding using heat energy from hot air, heating rollers, and the like have been widely used for hygiene products such as diapers, napkins, and pads, or for articles used in daily life and industrial materials such as filters because bulkiness can easily be obtained thereby. In particular, hygiene articles must be soft and feel comfortable because they are items in direct contact with the skin, and they must be absorbent because liquids such as urine and menstrual flow must be absorbed quickly. Many methods have been proposed for obtaining a fiber and nonwoven fabric that has bulkiness capable of expressing such performance.
Several items with improved recovery from compression have been proposed in the prior art. In Patent document 1, for example, elasticity is imparted to the fiber by using a thermoplastic elastomer, and recovery from compression is improved thereby. However, the use of a thermoplastic elastomer is essential in this method, and it is difficult to use the same in a hygiene product directly in contact with the skin because of the characteristic sticky feeling of the elastomer. In Patent document 2, although recovery from compression is improved by generating latent crimping in a side-by-side configuration, the combinations of resins with good compatibility for maintaining the fiber cross-section in a side-by-side configuration are limited in that method. Moreover, such prior art involves methods that improve recovery from compression, but there are almost no methods that improve compression resistance, i.e., methods that reduce the rate of decrease in bulkiness between under a light load and under a heavy load.
[Patent document 1] Japanese Patent Application Publication No. 2001-11763
[Patent document 2] Japanese Patent No. 2908454